United Nations warning ahead of climate talks

Average global temperatures will approximately climb as high as 3.4C by the end of the century. Photo / AP

The world's nations must urgently ramp up commitments to cut planet-warming carbon emissions to avoid "human tragedy", the United Nations warned yesterday.

As they stand, these commitments - which do not kick in until 2020 - would still allow average global temperatures to climb as high as 3.4C by the end of the century, a recipe for massive climate damage, the UN Environment Programme (UNEP) said in its annual Emissions Gap report.

"If we don't start taking additional action now, beginning with the upcoming climate meeting in Marrakesh, we will grieve over the avoidable human tragedy," said UNEP head Erik Solheim.

UN climate negotiators from 196 countries - tasked with implementing the landmark Paris climate pact which came into force yesterday - gather in the Moroccan city next week.

"The growing number of climate refugees hit by hunger, poverty, illness and conflict will be a constant reminder of our failure to deliver," Solheim said in a statement.

The UNEP report tracks the so-called global carbon budget - the total amount of greenhouse gases humanity can add to the atmosphere without pushing temperatures above the threshold of destructive global warming.

Going into the Paris climate summit last December, that red line had been set at 2C above pre-industrial era levels.

But a maelstrom of climate-enhanced natural disasters - including deadly storm surges, droughts, floods and wildfires - prompted nations to lower the danger threshold to "well below" 2C, and even 1.5C if possible.